Combine the bacon, mayonnaise, Parmesan cheese, and cream cheese in a food processor, and process until the bacon is chopped and the mixture is well blended. Season to taste with black pepper, and pulse a few more times to mix that in.
Scoop the dip into a serving dish and smooth the top. Sprinkle with lettuce, tomatoes, green onions, and Cheddar cheese. Stop, you're done.